1. Field of the Invention
The present invention relates to a purifying system for removing impurities which are mixed in working solution used in a manufacturing process.
2. Description of the Related Art
The working solution for use in a manufacturing process includes, for example, cleaning solution for use in a cleaning operation or grinding fluid (a coolant) for use in a grinding operation. In general, the foregoing working solutions encounter mixture of a variety of impurities. Therefore, when the working solution is recycled, the working solution must be purified before recycling.
As a means for purifying the working solution, a variety of suggestions have been made. For example, a technique has been disclosed in Japanese Patent Laid-Open No. Sho.58-174211. According to the foregoing disclosure, impurities, such as powder mainly composed of magnetic substances and produced due to a cutting operation, are adsorbed to a magnet drum. Then, impurities adsorbed to the magnet drum are separated and removed by a scraper. Moreover, deposited non-magnetic impurities, such as abrasive grains, are scraped and removed by a scraper chain.
In Japanese Patent Laid-Open No. Sho.59-39309, a technique has been disclosed with which an ultrasonic vibrating plate is provided for the side wall of the tank. Ultrasonic waves oscillated from the ultrasonic vibrating plate are used to oscillate impurities mainly composed of oil components mixed and suspended in the working solution to coagulate and float the same. Then, floated impurities are removed by a skimmer.
Another technique has been disclosed in Japanese Patent Laid-Open No. Hei.4-129643. According to the foregoing disclosure, a lower portion of a rotative plate having a surface in which a plurality of grooves are spirally or concentrically formed is vertically and downwards immersed into the working solution accumulated in a tank. Then, the rotative plate is slowly rotated to cause impurities floating on the liquid level of the working solution and mainly composed of oil components to adhere to the surface of the rotative plate so as to separate the impurities of the foregoing type from the working solution. Then, impurities allowed to adhere to the surface of the rotative plate is scraped by a scraper so as to be gathered in a purify portion.
In Japanese Patent Laid-Open No. Hei.3-294142, a technique has been disclosed with which a filter incorporating a filter cloth is applied to the body of a rotative drum. Then, cutting oil allowed to pass through the filter cloth and introduced into the rotative drum is pumped out from a conduit to a recovery tank.
Although the purifying system adapted to any one of the foregoing purifying methods or arranged by combining the foregoing methods with one another permits a somewhat satisfactory purifying effect, fine impurities of a type mixed in the working solution cannot be removed.
It leads to a fact that the working solution purified by the conventional purifying system adapted to any one of the foregoing purifying method encounters easy deterioration in the working solution owing to corrosion of the fine residues. Therefore, elongation of the changing cycle is undesirably limited. Hence it follows that the running cost and the cost required to dispose the waste solution cannot be reduced.
In view of the foregoing, an object of the present invention is to provide a purifying system which is capable of significantly improving performance for purifying working solution, which permits the working solution to repeatedly be used for a long time and which is able to reduce the running cost and the cost required to dispose waste solution.
To solve the above-mentioned problems, a first purifying system according to the present invention is a purifying system disposed in a circulating circuit for working solution for use in a manufacturing process, the purifying system comprising: a first purifying apparatus for removing impurities mixed in the working solution; and a second purifying apparatus disposed downstream of the first purifying apparatus and structured to furthermore purify the working solution purified by the first purifying apparatus, wherein the second purifying apparatus incorporates a working-solution accumulating tank for accumulating the working solution; a filter for vertically sectioning the working-solution accumulating tank at an intermediate position of the working-solution accumulating tank; a working-solution introducing pipe disposed in substantially a central portion of the working-solution accumulating tank such that the working-solution introducing pipe penetrates the filter and structured to diffuse and discharge the working solution supplied from the first purifying apparatus from a lower end of the working-solution accumulating tank; a weir formed at an upper end of the working-solution accumulating tank; an oil separating wall formed along the inner wall of the weir and having a lower end which is lower than the weir; and a solution gathering groove formed in the outer surface of the weir.
A second purifying system according to the present invention has a structure according to the first purifying system, wherein the bottom of the working-solution accumulating tank is formed into an inclined surface downwards inclined toward the central portion thereof, and a drain valve is disposed which is capable of discharging impurities deposited at the lower end of the inclined surface.
A third purifying system according to the present invention has a structure according the first purifying system or the second purifying system, a centrifugal separator which is capable of purifying the working solution supplied from the first purifying apparatus is disposed between the first purifying apparatus and the second purifying apparatus, and the centrifugal separator supplies separated working solution containing impurities to the second purifying apparatus.
A fourth purifying system according to the present invention has a structure according to the third purifying system, wherein the centrifugal separator adjusts the flow rate of the working solution which is supplied from the first purifying apparatus to the second purifying apparatus.
A fifth purifying system according to the present invention has a structure according to any one of the first to the fourth purifying system, wherein the first purifying apparatus incorporates a first tank chamber, and a scraper conveyor which is capable of discharging deposited and suspended impurities to the outside of the first tank chamber is provided for the first tank chamber.
A sixth purifying system according to the present invention has a structure according to the fifth purifying system, wherein the scraper conveyor incorporates a conveyor body and a plurality of scrapers, and the scraper are joined to the conveyor body such that displacement of the scraper is permitted.
A seventh purifying system according to the present invention has a structure according to the fifth purifying system, wherein the first purifying apparatus incorporates a second tank chamber formed adjacent to the first tank chamber at a position downstream of the first tank chamber, and sucking means for sucking floating impurities to return sucked impurities to the first tank chamber is provided for the second tank chamber.
An eighth purifying system according to the present invention has a structure according to the seventh purifying system, wherein the second tank chamber incorporates heating means for heating the working solution.
A ninth purifying system according to the present invention has a structure according to the seventh purifying system or the eighth purifying system, wherein the second tank chamber incorporates circulating means for circulating the working solution in the second tank chamber and corner plates which form curved portions in the corners of the second tank chamber.
A tenth purifying system according to the present invention has a structure according to any one of the seventh purifying system to the ninth purifying system, wherein the second tank chamber has a recess in which impurities can be deposited and which is formed in substantially the central portion of the bottom of the second tank chamber and a drain valve disposed at a lower end of the recess.